Most people who've asked about mains water cooling have been shot down because of the waste it would cause, but how about using the coldwater tank as the reservoir?, do most/all houses have a coldwater tank in their attics?, mine does, it's used to act as a 'buffer' for the 'mains', for when you use large amounts of cold water (baths, ect...), and incase of water outage?...
anyone considered this before?. it'd take a pump and a half to get the lift required though
, I'd leave the pump near the tank as well for the extra 'quiet', this could be an idea for people going for a 'totaly silent' solution...